More accurately, v1.x had the Logging & Instrumentation Application Block, and in v2 it was renamed to the Logging Application Block. There were a few reasons for the change:

The original name was chosen largely to play homage to the older Enterprise Instrumentation Framework (EIF), however since this became less important moving forward

Logging can be one type of instrumentation, but it's not the only type. However the block is really only about logging, so the name is potentially misleading.

In EntLib v2 we built a new component to handle instrumentation across all of the application blocks (i.e. perf counters, WMI and event logs, driven from configuration). Since this capability is distinct from the Logging Application Block, we didn't want
people to get confused by keeping the Instrumentation term in the block name.

In the last bullet, you mentioned that a new component was built to handle instrumentation. What is this component and is it used like the other application blocks or is it more like a utility component? Is there any docs associated with it?

It's more of a utility component. It was built primarily to support the blocks in EntLib, although you can use it in your own apps, blocks or frameworks if you have a similar need for configuration-controlled instrumentation.

There is a short doc topic on it under Design of Enterprise Library\Instrumentation. The code is in the Common assembly under the Common.Instrumentation namespace.